Patent GB-790274-A (GB)
Title: Improvements in or relating to electrostatic precipitators
IPC: B03C3/70
Filed: 1956-03-14
Abstract: 790,274. Electrostatic precipitation. PENNEY, G. W. March 14, 1956 [March 18, 1955], No. 8019/56. Class 39(1). The collecting cell B, Fig. 1, of a two stage precipitator comprises two series of electrically conducting plates 21, 22 alternating with each other across the width of the cell, and insulators 24 extending between and secured to the plates, which insulate the plates of one series from those of the other and also hold the plates of both series in position equidistant from each other along their lengths, the insulators 24 being long relative to their X-sectional area and having their longitudinal axes extending at an angle to the plates whereby the length thereof between plates provides sufficient creep to prevent sparkover. The plates are fabricated from stiff paper or card coated with metal foil or an electrically conductive varnish and may be made from two sheets coated on one side and placed together with the coating internal. The construction is such that the charge of the collected dust is conducted away with a low voltage drop. The insulators 24 may be relatively fine threads of nylon, shellacked cotton, silk or polythene extending alternately back and forth between adjoining plates, secured at intervals by staples 25, Fig. 2, and passing over notches 21a at the ends of the plates. Alternatively the threads may be passed through holes in the plates, with or without looping in the holes. In another embodiment the threads are secured to the plates by transverse strips of material glued to the surface of the plates. In another embodiment the plates are supported and mutually insulated by rigid plastic rods passed through the plates to form acute angles therewith and with their ends attached to the side plates 23 by short flexible tapes. Alternatively, flat non- conductive tapes of nylon or polythene or rigid corrugated non-conductive strips may be used instead of the threads 24. The two outside plates 23, are adapted to engage with members of the external casing. In all the above arrangements of insulators the plate structure is collapsible for storage and transport and may be inserted or removed as a unit into the casing. The plates 21 and 23 are earthed by wires 28 stapled, together with a small patch of metal foil 30, to the plates. The high potential plates 22 each have high resistance conductors 31 leading to a short wire 32 supported by a non-conducting thread 33 so that an assembly the wire 33 contacts a conductive past 34 connected to a high potential source. By this means the plate currents are limited to 5 x 10<SP>-4</SP> amps. The side plates 23 may be continued into the ionizing section A to form the earthed electrodes of that unit so that these too may be replaced by removal of the plate structure when dirty. Alternatively a separate disposable ionizing unit may be provided comprising two plate electrodes 46, Fig. 16, held together by straps 47, 48 with fold lines to permit collapsing for insertion or removal of the unit into the casing. The straps 47 also act as air flow baffles adjacent the ends of the ionizing wire which is supported by a yoke 50 and non-conducting members 51, 52. Specification 475,443 [Group XL], is referred to.